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[PATCH] i386: Selectable Frequency of the Timer Interrupt 

Make the timer frequency selectable. The timer interrupt may cause bus
and memory contention in large NUMA systems since the interrupt occurs
on each processor HZ times per second.

Signed-off-by: Christoph Lameter <christoph@lameter.com>
Signed-off-by: Shai Fultheim <shai@scalex86.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Lameter 2005-06-23 00:08:25 -07:00 committed by Linus Torvalds
parent 799d19f6ec
commit 5912100372
5 changed files with 57 additions and 3 deletions
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2
arch/i386/Kconfig
View File

@ -961,6 +961,8 @@ config SECCOMP
If unsure, say Y. Only embedded should say N here.
source kernel/Kconfig.hz
endmenu

2
arch/x86_64/Kconfig
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@ -402,6 +402,8 @@ config SECCOMP
If unsure, say Y. Only embedded should say N here.
source kernel/Kconfig.hz
endmenu
#

4
include/asm-i386/param.h
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@ -1,8 +1,10 @@
#include <linux/config.h>
#ifndef _ASMi386_PARAM_H
#define _ASMi386_PARAM_H
#ifdef __KERNEL__
# define HZ 1000 /* Internal kernel timer frequency */
# define HZ CONFIG_HZ /* Internal kernel timer frequency */
# define USER_HZ 100 /* .. some user interfaces are in "ticks" */
# define CLOCKS_PER_SEC (USER_HZ) /* like times() */
#endif

6
include/asm-x86_64/param.h
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@ -1,9 +1,11 @@
#include <linux/config.h>
#ifndef _ASMx86_64_PARAM_H
#define _ASMx86_64_PARAM_H
#ifdef __KERNEL__
# define HZ 1000 /* Internal kernel timer frequency */
# define USER_HZ 100 /* .. some user interfaces are in "ticks */
# define HZ CONFIG_HZ /* Internal kernel timer frequency */
# define USER_HZ 100 /* .. some user interfaces are in "ticks */
#define CLOCKS_PER_SEC (USER_HZ) /* like times() */
#endif

46
kernel/Kconfig.hz Normal file
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@ -0,0 +1,46 @@
#
# Timer Interrupt Frequency Configuration
#
choice
prompt "Timer frequency"
default HZ_250
help
Allows the configuration of the timer frequency. It is customary
to have the timer interrupt run at 1000 HZ but 100 HZ may be more
beneficial for servers and NUMA systems that do not need to have
a fast response for user interaction and that may experience bus
contention and cacheline bounces as a result of timer interrupts.
Note that the timer interrupt occurs on each processor in an SMP
environment leading to NR_CPUS * HZ number of timer interrupts
per second.
config HZ_100
bool "100 HZ"
help
100 HZ is a typical choice for servers, SMP and NUMA systems
with lots of processors that may show reduced performance if
too many timer interrupts are occurring.
config HZ_250
bool "250 HZ"
help
250 HZ is a good compromise choice allowing server performance
while also showing good interactive responsiveness even
on SMP and NUMA systems.
config HZ_1000
bool "1000 HZ"
help
1000 HZ is the preferred choice for desktop systems and other
systems requiring fast interactive responses to events.
endchoice
config HZ
int
default 100 if HZ_100
default 250 if HZ_250
default 1000 if HZ_1000